Stabilization of organic compounds



Patented May 29, 1951 STABILIZATION OF ORGANIC COMPOUNDS Ralph B. Thompson and Joseph A. Chenicek,

Riverside, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application January 29, 1948, Serial No. 5,210

13 Claims.

This invention relates to the stabilization of organic compounds which tend to deteriorate in storage or in use .due to oxidation reactions.

Various organic compounds are unstable in storage or during treatment and form undesirable gums, undergo discoloration, form sludges or otherwise deteriorate due to oxidation, polymerization or other undesired reactions. Included among the organic compounds which undergo such deterioration are gasoline, Diesel oil, mineral oil, lubricating oil, fuel oil, drying oil, greases, edible fats and oils, acetylenes and particularly vinyl acetylene, butadiene, isoprene, styrene and other vinyl aromatics, various unsaturated alcohols, acids, ketones, etc.

The invention is particularly applicable to the stabilization of unsaturated gasolines and particularly cracked and polymer gasolines. In storage or during treatment these unsaturated gasolines tend to form undesirable gums. The invention is also applicable to the treatment of aviation gasolineswhich tend to undergo deterioration due to the addition of tetraethyl lead fluid or due to other components in the gasoline.

The invention is also particularly applicable to the stabilization of edible fats and oils which generally are of animal or vegetable origin and which tend to become rancid, especially during long'periods of storage prior to use. Typical representatives of these edible fats and oils include linseed oil, menhaden oil, cod liver oil, castor oil, olive oil, rapeseed oil, coconut oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, butter, fat, lard, beef tallow, etc. It is understood that other oils and fats may be treated within the scope of the present invention, including oils and fats which previously have been subjected to various treatments, such as blowing with air, heat treatment, etc.

In another embodiment the present invention is particularly applicable to the treatment of crops by dusting or spraying in order to preserve food accessory factors such as carotene, vitamins,

various fatty acids, alcohols, etc.

relates to a method of stabilizing motor fuel normally tending to deteriorate in storage which comprises adding thereto from about 0.001% to about 0.5% by weight of2,2-dimethyl-5-hydroxy- 2,3,6,'7,8,9-hexahydronaphtho-(1,2-b) -furan.

In another specific embodiment the present invention relates to a method of stabilizing edible fats and oils against rancidity which comprises adding thereto from about 0.001% to about 0.5% by weight of 2,2,7-trimethy1-5-hydroxy-2,3,6,9- tetrahydronaphtho- (1,2-b) -furan.

In another embodiment the present invention relates to organic compounds normally tending to deteriorate in storage, and particularly motor fuel or edible fats and oils, containing a small amount of the inhibitors herein set forth.

In accordance with the present invention, stabilization of unstable organic compounds is effected by adding thereto a small amount of a particular class of inhibitors which are illustrated by the following general structures:

OH I OH R2 I R2 i R t e R/ Rl I II on R2 m R; C J7 A R R1 III Iv on OH R 2 R2 0 R 0 2* i O\ 0 R, o

R R V VI R, R1, R2 and/or R3 comprise hydrogen or alkyl radicals. When these groups comprise alkyl rad- Furan compounds Pyran compounds 3 4 8 C C 9 l l -General-structure I above illustratesa 5-hy- .droxy-2,3 dihydronaphtho- (1,2.-b) -furan. .Iar-

ticularlysatisfactory inhibitors of this class .in-

.clude such compounds as 5-hydroxy-2,3-dihydro- 'naphtho- (1,2-b) -furan, 2,2-dimethyl-5-h-ydroxy- .2, 3-dihydronaphtho- (1,2-b) furan, ;.2,2,'7.tri- :methyl-B-hydroxy-Z, 3-dihydronaphtho- (12 -.b) .furan, etc.

:Structure 11 illustrates a 6-hydroxy-3A-dihydronaphtho-(l,2-b) -pyran. Particularly satisfactory inhibitors of this class include such compounds as 6 hydroxy 3,4 dihydronaphtho- (1,2-b) -pyran, 2,2-dimethyl-6-hydroxy-3A-dihy- -dronaphtho-(l-,2-b) -pyran, 2,2,8-trimethyl-d-hyd-roxy-BA-dihydronaphtho-(1,2-b) -pyran, etc.

Structure III illustrates a- 5-hydroxy-2,3,6,9--

tetrahydronaphtho- (1,2-b) -furan. Particularly satisfactory inhibitors of this class include-such compounds as 5-hydroxy-2,3,6,9-tetrahydronaphtho (1,2-b) furan, 2,2 --dimethyl- 5 hydroxy- 2,3,6,9-tetrahydronaphtho-(1,2-b) -furan, 7 2,2,7- trimethyl-5-hydroxy 2,3,6,Q-tetrahydronaphtho- (1,2-b) -furan, etc.

StructureIV illustrates a 6-hydr oxy-3,4;,7,ltetrahydronaphtho- (1,2-b) -pyran. "Particularly satisfactoryinhibitors of this class include such compounds as 6-hydroxy.,-3,4,7,l0-tetrahydronaphtho--(l,2-b) -pyran, 2,2-dimethyl-6-hydroxy- 3,4,7,10-:tetrahydronaphtho-(1,2-b) pyran, 2,2,8- trimethyl- 6 -hydroxy 3,4,'7,10 tetrahydronaphtho-(1,2-b) -pyran, etc.

Structure V illustrates a -hydroxy-2,3,6,7,8,9- hexahydronaphtho- 1,2-b) -furan. Particularly satisfactory inhibitors of this class include such compounds as 5-hydroxy-2,3,6,7,8,9-hexahydronaphtho-(1,2-b) -furan, 2,2-dimethyl-5-hydroxy- 2,3,6,'7,8,9 hexahydronaphtho (1,2-b). iuran, 2,2,7-trimethyl-5-hydroxy 2,3,6,'7,8,9-hexahydronaphtha-(1,2-b)-furan etc.

Structure VI illustrates a 6-hydroXy-3,4,7,8,9,l0- hexahydronaphtho- 1,2-b) -pyran. Particularly satisfactory inhibitors of this class include such compounds as 6-hydroxy-3,4,7,8,9,l0-hexahydronaphtho- (1,2-b) -pyran, 2,2-dimethyl-6-hydroxy- 3,43,83,10 hexahydronaphtho -(l,2-b) pyran, 2,2,8-trimethyl 6 hydroxy-3, l,7,8,9,l0ehexahydronaphtho- (1,2-b) -pyran, etc.

It is understood that the compounds hereinbe- :fore set forth comprise preferred inhibitors and that compounds of these general structures sub- .stituted by suitable groups are also combined within the scope of the present invention. However, as hereinbefore set forth, it is preferred pron-aromatic, alicyclicring has shifted to a nonconjugated position and/or those in which the hydroxy group and furan or pyran ring have interchanged positions with respect to an alkyl group posit'ionedon the non-aromatic alicyclic ring. ,In;the-other, two types of compounds, the

,,,-,i5 omer's willbe.ofthe latter type.

];he ip h ibitors; of the present invention may be preparedjn any suitable manner. In one method of preparing 2,2-dimethyl-5-hydroxy- 2,3 ,'6;7,8;9=hexahy.dronaphtho- (1,2-b) -f-uran, 1,4- dihydroxy-5,6,7,S-tetrahydronaphthalene is dissolvedinlan aqueous organic solvent containing an alkaline material and is reacted with methallyl chloride. The reaction is effected.by boiling under-refiuxing.conditions, after which the product may be acidified and extracted witherganicsolvents. The unreacted. starting material may be separated by extraction withdilute aqueous caustic solution and the m onomethallyl ether may be recovered by extraction with-Clais'en solution; The monornethallyl ether is isomeriaed by boiling with din' ethylaniline or the like,,the dimethylaniline is removed with dilute,acid,.- and ring closure is effected by boilingwith a suitable acid such as 90% formic acid. The. acid is then removed by distillation andthe product is purified by distillation in vacuum. The other naphtha fmans may be prepared in substantially thesa'me -manr 1er=.but varying thestarting; reagents as {deired- :2 ,2.-dirnethyl 6 --hydroxy-3,4,7,8,9,lll-hexahydronaphtho-(LZ-b) pyran may be prepared by Warmin a sus o of .lA-Q YQIPXY- Ffitetrahydronaphthalene andisoprene in a suitable solvent,such asglacialacetic acid which ha'sbeen saturated,,with .anhydrous hydrogen, chloride. After the reaction has proceeded to completion, the .productis extracted with an organic solvent, such as ether-petroleum ether,.. and the acetic acidtis removed-by treatment with a. suitable base such as ,sodium bicarbonate. The unreacted starting-material may be removed byextraction witha dilute-aqueous caustic solution and the final product'may be purified by distillation Lunder vacuum.

"When it isdesired to add other alkyl group or groups to either pne or both of the rings, itmay -be effected in any suitable manner. For example, butylation may be efiected bydissolving the hydronaphtho furan or pyran in acetic acid andadding thereto a suitable catalyst such as phosphoric acid. Tertiarybutyl alcohol is thenadd- ,ed and the mixture rnay be heated to a" temperature of 60-85? C. with constant stirring, after whic h p odu t m e. e e ii fi Water, extracted first with organic solvents and t'l'ien with Claisen solution and iinally distilled in vacuum The inhibitorof the. present invention r senerally. a dedt or n c. mat ia i amou of ,le's'sthan 1% byweight and generally within the,. range,,of f rom about 0.001% to about 0.5%. When used in ,g'asoline, it is understood that the nhibi r.ma baused n conjuncti n i hv ou .dycs,metal .deactivators, ,anti lgnock agents such as tetraethyl lead, etc. When, used i edible'fats enchi at. is. un rst d. t t t inhi i or be used in conjunction with a synergist, such as phophoric acid, ascorbic acid, etc.

The following examples are introduced to further illustrate the novelty and utility of the present invention but not with the intention of unduly limiting the same.

The inhibitors used in the following runs were prepared in a manner similar to that heretofore set forth.

EXAMPLE I The following runs were made with a lard which had a normal stability period of 3 hours as determined by the Swift test. This test is described in detail in the article by A. E. King, H. L. Roschen and W. H. Irwin, which appeared in the Oil and Soap, vol. X, No. 6, pages 105 to 109, (1933). In general, this test comprises bubbling air through a sample of the lard and reporting the number of hours until the lard develops a peroxide value of 20.

0.02% by weight of the inhibitor was added to different samples of the lard and gave the results as shown in Table 1.

Table 1 Stability Inhibitor Period,

Hours 2,2,7 trimethyl 5 hydroxy 2,3,6,9 tetrahydronaphtho (1,2-b) furan 50 2,2- dimethyl 5 hydroxy- 2,3,6,Z,8,9- hexahydronaphtho 2-b)-furan 23 2, 2, 7-trimethyl-5- hydroxy-2,3, 6, 7,8,9-hexahydronaphtho (1,2- -furan 31 2,2-dimethyl- 6 -hydroxy- 3,4,7,8,9, IO-hexahydronaphtho (1,2-b)-pyrau 32 2, 2,8-trimethyl-6-hydroxy-3,4,7,8,9, l-l1exahydronaphtho- 2-b) pyran 32 It will be noted from the data in the above table that the various inhibitors of the present invention considerably increased the stability period of the lard.

EXAMPLE II The following tests were made with a Pennsylvania cracked gasoline which had an uninhibited induction period of 100 minutes. 0.025% by weight of inhibitor was added to different samples of the gasoline and gave the results as shown in Table 2.

It will be noted from the data in the above table that the inhibitors of the present invention considerably increased the induction period of the gasoline.

We claim as our invention:

1. A method of stabilizing motor fuel normally tending to deteriorate in storage which comprises adding thereto a -hydroxy-2,3,6,9-tetrahydronaphtho- 1,2 b) furan.

2. A method of stabilizing motor fuel normally tending to deteriorate in storage which compr se adding thereto a 5-hydroxy-2,3,6,'7,8,9-hexahydronaphtho- (1,2-b) furan.

3. A method of stabilizing cracked gasoline which comprises adding thereto from about 0.001% to about 0.5% by weight of 2,2-dimethyl- 5-hydroxy-2,3,6,7,8,9 hexahydronaphtho (1,2- b) furan.

4. A method of stabilizing edible fats and oils against rancidity which comprises adding thereto an inhibitor comprising a 5-hydroxy-2,3,6,7, 8,9-hydronaphtho- (1,2-b) furan.

5. A method of stabilizing edible fats and oils against rancidity which comprises adding thereto an inhibitor comprising a 5-hydroxy-2,3,6,9-tetrahydronaphtho-(1,2-b) furan.

6. A method of stabilizing lard which comprises adding thereto from about 0.001% to about 0.5% by weight of 2,2,7-trimethyl-5-hydroxy-2,3,6,9- tetrahydronaphtho- 1,2 b) furan.

7. An organic material normally subject to oxidative deterioration containing, as an inhibitor for said deterioration, a small amount of a 5-hydroxy-2,3,6,9tetrahydronaphtho-(1,2-b) furan.

8. An organic material normally subject to oxidative deterioration containing, as an inhibitor for said deterioration, a small amount of a 5-hydroxy-2,3,6,7,8,9 hexahydronaphtho (1,2 b) furan.

9. Cracked gasoline containing from about 0.001% to about 0.5% by weight of 2,2-dimethyl- 5-hydroxy-2,3,6,7,8,9 hexahydronaphtho (1,2 b) furan.

10. Edible fats and oils normally tending to become rancid containing from about 0.001% to about 0.5% by weight of 2,2,7-trimethyl-5-hydroxy-2,3,6,9tetrahydronaphtho- (1,2-b) furan.

11. Edible fats and oils normally tending to become rancid containing, as an inhibitor to re tard rancidity development, a 5-hydroxy-2,3,6,9- tetrahydronaphtho- 112 b) furan.

12. A method of stabilizing an organic material normally subject to oxidative deterioration which comprises adding thereto an inhibitor comprising a tricyclic compound containing the naphthalene ring system having fused to one of its benzene rings, by a carbon atom and a heterocyclic oxygen atom, a member of the group consisting of dihydro furan and dihydro pyran rings, said one benzene ring having a hydroxy group in the position para to said heterocyclic oxygen atom.

13. An organic material normally subject to oxidative deterioration containing, as an inhibitor for said deterioration, a small amount of a tricyclic compound containing the naphthalene ring system having fused to one of its benzene rings, by a carbon atom and a heterocyclic oxygen atom, a member of the group consisting of dihydro furan and dihydro pyran rings, said one benzene ring having a hydroxy group in the position para to said heterocyclic oxygen atom.

RALPH B. THOMPSON. JOSEPH A. CHENICEK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,283,388 Paul May 19, 1942 2,363,687 Paul Nov. 28, 1944 2,383,043 Cline Aug. 21, 1945 OTHER REFERENCES Mattill, Oil and Soap, January 1945, pp. 1-3. 

12. A METHOD OF STABILIZING AN ORGANIC MATERIAL NORMALLY SUBJECT TO OXIDATIVE DETERIORATION WHICH COMPRISES ADDING THERETO AN INHIBITOR COMPRISING A TRICYCLIC COMPOUND CONTAINING THE NAPHTHALENE RING SYSTEM HAVING FUSED TO ONE OF ITS BENZENE RINGS, BY A CARBON ATOM AND A HETEROCYCLIC OXYGEN ATOM, A MEMBER OF THE GROUP CONSISTING OF DIHYDRO FURAN AND DIHYDRO PYRAN RINGS, SAID ONE BENZENE RING HAVING A HYDROXY GROUP IN THE POSITION PARA TO SAID HETEROCYCLIC OXYGEN ATOM. 